JP2012097618A - Compression apparatus and operation control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frequency in control of a compressor to prevent failure of a compressor, burning of a motor, or the like, while performing energy-saving operation in which pressure of discharge compression gas of the compressor is suppressed.SOLUTION: Control time T is set based on service lives of air compressors 12a-12d and peripheral equipment thereof, and the time when the number of loads of the air compressors is changed is set as a starting point tof the control time T. After the lapse of the control time T, when a pressure variation ΔP of the discharge compression gas from the starting point tbecomes a set increment ΔPor more, a controller 30 controls electromagnetic switches 16a-16d, so that unloading switching control in which one compressor is changed from loading to unloading is performed.

Description

  The present invention produces compressed gas using a plurality of compressors, and adjusts the number of operating compressors according to the amount of compressed gas consumption, while ensuring the necessary pressure and required flow rate of the compressed gas. The present invention relates to a compressor and an operation control method thereof.

  In factories and the like, a gas compression device is provided in order to supply compressed gas to a section that requires compressed gas such as compressed air. In such a gas compression device, the flow rate of the compressed gas is ensured while ensuring the necessary discharge pressure. As a gas compression device, a device in which a plurality of compressors are arranged in parallel, and discharge pipes of the compressors are connected to a compressed air storage tank via a collection pipe is known.

  In this gas compression apparatus, a pressure sensor is provided in the compressed air storage tank or the discharge collecting pipe, or a flow rate sensor is provided in a pipe that supplies compressed gas to the consumption side (load side). Then, the detection values of these sensors are compared with preset threshold values, and load / unload and start / stop control of each compressor are performed. Thereby, the number of operating compressors is increased or decreased according to these detected values, and the discharge amount of the compressor is adjusted. In such a gas compression apparatus, the compressor is operated at a pressure as low as possible to reduce power consumption and improve the life of the compressor.

  For example, in Patent Document 1, a plurality of air compressors arranged in parallel and discharge pipes of the respective air compressors are connected to the compressed air storage tank via a collection pipe to detect the pressure in the compressed air storage tank. A compression apparatus having a pressure sensor is disclosed. As the plurality of compressors, compressors having substantially the same capacity are used, the predetermined pressure lower limit value and upper limit value are divided into the same number of pressure levels as the number of compressors, and the discharge pressure detection signal is the target. An operation control method is disclosed in which the number of compressors to be operated is changed when the pressure level is out of the range and the boundaries between the pressure levels are reached.

  FIG. 12 shows the operation control method disclosed in Patent Document 1. This operation control method is when eight compressors are used, and the lower limit pressure (for example, 0.6 MPa) and the upper limit pressure (for example, 0.7 MPa) of the discharge compressed air are divided into eight pressure levels. is doing. Until the detection signal P of the compressed air in the compressed air storage tank detected by the pressure sensor reaches the pressure level 1/8, all the eight compressors are operated, and thereafter the pressure level is reduced from 1/8 to 1 rank. Each time it goes up, the number of operating compressors will be reduced by one.

  Patent Document 2 or Patent Document 3 discloses an operation control method for reducing power consumption by controlling the discharge capacity of an air compressor according to the amount of compressed air consumed. In this operation control method, the discharge flow rate or discharge pressure of compressed air is detected, the change amount of the discharge flow rate or discharge pressure per unit time of compressed air is obtained, and the increase / decrease tendency of the compressor is determined from this change amount. The number of operating compressors is controlled according to the increasing / decreasing tendency.

JP 2004-340024 A JP 2003-35273 A JP 2007-120497 A

  In the operation control method disclosed in Patent Document 1, it is necessary to increase the number of compressors as the pressure control becomes finer. As the number of compressors increases, switching between start and stop, or load (load) and unloading are performed. It is necessary to frequently switch loads (no load). Therefore, there is a problem that the compressor is easily broken and the motor is easily burned out. In addition, the control system is more likely to cause abnormalities and failures due to the increased control frequency.

  Further, the operation control method disclosed in Patent Document 2 or Patent Document 3 obtains a change amount of the discharge flow rate or discharge pressure of the compressed air per unit time, and changes the number of operating compressors in accordance with the change amount. Therefore, the more accurate pressure control is performed, the shorter the unit time, the more frequently the start and stop of the compressor are switched, and the load and unload are switched, resulting in the same problem as in Patent Document 1.

  In view of the problems of the prior art, the present invention is directed to energy-saving operation that suppresses the pressure of the compressed gas discharged from the compressor, while reducing the control frequency of the compressor, thereby causing compressor failure, motor burnout, etc. The purpose is to prevent.

  In order to solve the above problems, the operation control method of the compression device of the present invention is to unload and load each compressor according to the flow rate used while detecting the pressure of the compressed gas discharged from a plurality of compressors. The control time is set based on the life of the compressor and its peripheral equipment, and the time when the number of compressors loaded is changed is set as the starting point of the control stop time. In addition, when the pressure change amount of the discharge compressed gas from the start point becomes equal to or greater than the set increase amount after the control stop time has elapsed, unload switching control for switching one compressor from loading to unloading is performed. Is.

The gist of the method of the present invention will be described with reference to FIG. FIG. 1 shows an example of operation control when there are four compressors. In the figure, P is the discharge pressure of the compressed gas, and the control time T is set in advance based on the lifetime of the compressor and its peripheral devices. A load volume changes are A ₁ of the first compressor, setting the control time T for the changes A ₁ and starting point t _0, the change amount ΔP of the discharge pressure P after the control time T has elapsed When the preset increase amount is exceeded, unload switching control for switching one compressor from loading to unloading is performed.

The same control is performed at the next change point A ₂ , a control time T is set with the change point A ₂ as the start point t _0, and after the control time T has elapsed, the change amount ΔP of the discharge pressure P is greater than the set increase amount. At that time, the unload switching control is performed. The unload switching control is not performed before the control time T elapses, and even after the control time T elapses, the unload switching control is not performed unless the pressure change amount ΔP becomes equal to or greater than the set increase amount.

In the method of the present invention, the control time is set starting from when the number of compressors is changed, and the unload control is not performed before the control time elapses. By reducing the number, it is possible to prevent a compressor failure or a motor burnout.
In addition, since the unload switching control is performed when the pressure change amount of the discharge compressed gas after the control time elapses exceeds the set increase amount, the pressure of the discharge compressed gas can be kept low as a whole. Therefore, power consumption can be reduced and the life of the compressor can be improved.

  In the present invention, the method for bringing the compressor into an unloaded state includes a method for stopping the motor that drives the compressor, a method for continuously driving the compressor and closing the suction side of the compressor, Examples of the method include a method in which the driving is continued and the suction side of the compressor is opened, and a method in which the driving of the compressor is continued and the discharge side is opened and is not discharged to the use side.

In the method of the present invention, when the pressure of the discharge compressed gas drops to a preset lower limit pressure, it is preferable to preferentially switch one compressor from unloading to loading. The gist of this operation control method is illustrated and described with reference to FIG. In the figure, when B where the discharge pressure P of the compressed gas becomes lower pressure P _L, preferentially increase one loading number of the compressor. This prevents the pressure of the discharge compressed gas is lowered than the lower limit pressure P _L, can be operated with the compressor in a proper pressure range.

In the method of the present invention, when the pressure of the discharge compressed gas rises to a preset upper limit pressure, one compressor may be preferentially switched from loading to unloading. The gist of this operation control method is illustrated and described with reference to FIG. In the figure, after the control time T has elapsed from the first change point (not shown), the unload control is performed at the second change point A ₂ where the change amount ΔP of the discharge pressure P is equal to or greater than the set increase amount. Yes. Changes A ₂ and later, control time T without has not elapsed (t <T), when the discharge pressure P becomes the upper limit pressure P _H C, and preferentially load the number of the compressor reduces one Yes. This prevents the compressor from being overloaded and allows the compressor to operate within an appropriate pressure range.

In the method of the present invention, a minimum load pressure belonging to a pressure range higher than the lower limit pressure of the discharge compressed gas and close to the lower limit pressure is set in advance, and unload switching control is performed in a pressure range higher than the minimum load pressure. Good. The gist of this operation control method is illustrated and described with reference to FIG. In the figure, when the discharge pressure P does not reach the minimum load pressure P _M, even if the condition is satisfied in the control time T and the pressure change amount [Delta] P, it does not perform the loading volume change of the compressor. When the discharge pressure P reaches the minimum load pressure P _M, at the time when the control time T has elapsed from the starting point t ₀ (D ₁ and D _2), the change amount ΔP of the discharge pressure P becomes the set increment or Then, unload switching control is performed. Incidentally, at the start operation, when loading quantity change compressor at the start of operation, i.e., regarded as the starting point t _0.

  If the minimum load pressure is not set, when the unload switching control is performed when the discharge pressure P is close to the lower limit pressure, the discharge pressure P immediately reaches the lower limit pressure, the unload switching control, the compressor Therefore, the load switching control for increasing the number of loads by one occurs in a very short time. This causes a failure of a control device such as a compressor. Therefore, by setting the minimum load pressure and preventing the unload switching control from occurring when the discharge pressure P is between the lower limit pressure and the minimum load pressure, the failure of the control device can be eliminated.

  Further, in the method of the present invention, an unload acceleration pressure belonging to a pressure region lower than the upper limit pressure and close to the upper limit pressure is set in advance, and when the control time elapses in a pressure region higher than the unload acceleration pressure, one unit It is better to switch the compressor from loading to unloading. At this time, the pressure change amount ΔP of the discharge pressure P from the start point of the control time does not matter.

The gist of this operation control method is illustrated and described with reference to FIG. In the figure, when the discharge pressure P reaches the upper limit pressure at point E, the number of compressor loads is preferentially reduced by one as described above. Then, it sets the control time T to the point E as the start point t _0, when the control time T has elapsed, to reduce one loading number of the compressor. As a result, by increasing the rate of decrease in the discharge pressure P in a high pressure region that is equal to or higher than the unload acceleration pressure, it is possible to reduce power consumption and to suppress failure of the compressor and the like.

  The compression apparatus of the present invention that can be directly used for carrying out the method of the present invention comprises a plurality of compressors, a pressure sensor that detects the pressure of compressed gas discharged from the compressors, and each compressor individually. In the compressor comprising the unloading means for unloading and a controller for controlling the unloading means to switch between loading and unloading of each compressor, the controller has a preset control time. The stored storage unit, a timer that measures time starting from the time when the number of compressors loaded is changed, and the time measured by the timer exceeds the control time, and the discharge compressed gas from the starting point An unloading unit that controls the unloading means to perform unload switching control for switching one compressor from loading to unloading when the pressure change amount exceeds a set increase amount. In which comprises a control unit.

In the device of the present invention, the control time is set based on the life of the compressor and its peripheral devices, the control stop time is set starting from the change in the number of compressors loaded, and the compression is performed until the control stop time elapses. Do not change the number of machines loaded. Thereby, since the control frequency of the compressor is regulated by the control time, it is possible to prevent compressor failure, motor burnout, and the like.
In addition, when the pressure change amount of the discharge compressed gas becomes equal to or greater than the set increase amount after the control time has elapsed, the unload switching control is performed, so that the pressure of the discharge compressed gas can be suppressed as a whole. As a result, power consumption can be reduced and the life of the compressor can be improved.

  In the device of the present invention, the lower limit pressure of the discharge compressed gas is preset and stored in the storage unit, and the controller preferentially loads one compressor from unloading when the discharge compressed gas falls to the lower limit pressure. A lower limit pressure control unit for controlling the unloading means may be provided so as to switch to Thereby, the pressure of the discharge compressed gas is prevented from falling below the lower limit pressure, and the compressor can be operated within an appropriate pressure range.

  In the present invention device, the upper limit pressure of the discharge compressed gas is preset and stored in the storage unit, and the controller preferentially loads one compressor from the load when the discharge compressed gas reaches the upper limit pressure. An upper limit pressure control unit that controls the unloading means may be provided so as to switch to unloading. This prevents the compressor from being overloaded and allows the compressor to operate within an appropriate pressure range.

  In the device of the present invention, the lowest load pressure belonging to the pressure range higher than the lower limit pressure and close to the lower limit pressure is preset and stored in the storage unit, and the unload control unit of the controller is in a pressure region above this minimum load pressure. The unloading means may be controlled so as to perform unload switching control. This eliminates frequent load unit control for loading and unloading of the compressor when the discharge pressure is close to the lower limit pressure, thereby preventing failure of the control device such as the compressor.

  Further, in the device of the present invention, an unload acceleration pressure belonging to a pressure range lower than the upper limit pressure and close to the upper limit pressure is preset and stored in the storage unit. In the area, when the control time has elapsed, the unloading means may be controlled so that one compressor is switched from loading to unloading. As a result, by reducing the discharge pressure P in a high pressure region that is equal to or higher than the unload acceleration pressure, it is possible to reduce power consumption and to suppress failure of the compressor.

  According to the method of the present invention, in the operation control method for a compressor, the pressure of compressed gas discharged from a plurality of compressors is detected and the compressor is switched between unloading and loading according to the flow rate used. The control time is set based on the life of the compressor and its peripheral devices, and the time when the number of compressors loaded is changed is set as the start point of the control time, and the discharge compressed gas from the start point after the control time has elapsed. When the amount of change in pressure exceeds the set increase, unload switching control is performed to switch one compressor from loading to unloading, so that the number of compressor loads can be changed within the control time. Since this is not performed, it is possible to reduce the frequency of changing the number of compressors loaded, and to prevent compressor failure, motor burnout, and the like. In addition, since the unload switching control is performed when the pressure change amount of the discharge compressed gas after the control time elapses exceeds the set increase amount, the pressure of the discharge compressed gas of the compression device can be kept low as a whole. This can reduce power consumption and improve the life of the compressor.

  According to the apparatus of the present invention, a plurality of compressors, a pressure sensor for detecting the pressure of the compressed gas discharged from the compressors, unloading means for individually unloading each compressor, and the unloading In the compressor having a controller that controls the means to switch between loading and unloading of each compressor, the controller includes a storage unit that stores a preset control time, and the number of compressors loaded is changed. A timer that measures the time from the start point of time, and when the time measured by the timer exceeds the control time and the pressure change amount of the discharge compressed gas from the start point exceeds the set increase amount, And an unload control unit for controlling the unloading means so as to perform unload switching control for switching the compressor from loading to unloading. Effect can be obtained.

It is explanatory drawing which illustrated the summary of the method of this invention. It is explanatory drawing which illustrated another summary of the method of this invention. It is explanatory drawing which illustrated another another point of this invention method. It is explanatory drawing which illustrated another another point of this invention method. It is explanatory drawing which illustrated another another point of this invention method. 1 is an overall configuration diagram of a compression apparatus according to a first embodiment of the method and apparatus of the present invention. It is a flowchart which shows the control procedure of the said compression apparatus. It is a flowchart which shows the control procedure of the 1st unload control in FIG. It is a flowchart which shows the control procedure of the 2nd unload control in FIG. It is a pressure control figure which shows an example of the operation control of the said compression apparatus. It is a pressure control figure which shows another example of the operation control of the said compression apparatus. It is a pressure control figure which shows an example of the operation control of the conventional compressor.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified.

(Embodiment 1)
A first embodiment of the method and apparatus of the present invention will be described with reference to FIGS. In FIG. 6, the compression apparatus 10 includes four air compressors 12a to 12d. As unloading means for putting the air compressors 12a to 12d into an unloaded state, electromagnetic switches 16a to 16d for controlling on / off of the motors 14a to 14d of the air compressors 12a to 12d are provided. Note that the unloading means is not limited to this.

  Other examples of the unloading means include (1) means using an intake valve and (2) means using an air discharge valve. Specifically, (1) the means using the intake valve continues to drive the compressor as it is, and performs no-load operation by changing the intake valve to reduce the intake amount of the compressor. This applies mainly to screw compressors. Further, another means using the intake valve continues to drive the compressor as it is, and performs no-load operation by opening the intake valve. This applies mainly to reciprocating compressors. (2) The means using the air discharge valve continues the driving of the compressor as it is, and opens the air discharge valve provided on the discharge side to perform no-load operation.

  The compressor 10 mainly includes motors 14a to 14d that are connected to a power source 18 and drive air compressors 12a to 12d, electromagnetic switches 16a to 16d that control on / off of the motors 14a to 14d, and air compressors 12a to 12d. Collective discharge pipe 20 in which the respective discharge pipes d are gathered, an air tank 22 connected to the collective discharge pipe 20, a pressure sensor 24 for detecting the pressure of the discharge air flowing through the collective discharge pipe 20, and an air compressor 12a A controller 30 for switching between loading and unloading of .about.d.

  In the load operation, the electromagnetic switches 16a to 16d are turned on by the controller 30, and the motors 14a to 14d are rotated to drive the air compressors 12a to 12d. Air sucked from the intake ports of the air compressors 12a to 12d is compressed by the rotation of the motors 14a to 14d and discharged from the discharge ports. The discharge compressed air is stored in the air tank 22 via the collective discharge pipe 20 and is pressurized to a predetermined pressure. The compressed air once stored in the air tank 22 is appropriately supplied to a use destination (not shown) via the compressed air supply pipe 26.

In FIG. 6, an intake side valve device such as an intake valve that adjusts the intake amount, a discharge valve device that adjusts the discharge amount, a discharge side valve device such as a check valve that prevents backflow of discharge air, and an abnormal pressure rise are prevented. Safety valves and peripheral devices such as filters, dryers, and aftercoolers are omitted.
The air compressors 12a to 12d suck the working fluid into the compression chambers, compress the working fluid by the compression means driven by the motors 14a to 14d, and generate compressed air. The type of the compressor is not limited, but may be any of a positive displacement compressor such as a screw type, a reciprocating type (reciprocating type), a scroll type, or a turbo type compressor such as a centrifugal type or an axial flow type.

The controller 30 includes a timer 32 that measures time, a calculation unit 34 that performs various calculations, and a storage unit 36 that stores various set values. Timer 32 measures the time t the time of changing the load number of the compressor 12a~d as a starting point t _0. It should be noted that, at the start of operation, is regarded as the starting point t ₀ the at the start of operation to measure the time t. The calculation unit 34 includes an unload control unit 38, a lower limit pressure control unit 40, and an upper limit pressure control unit 42.

The storage unit 36 are stored and T preset control time, and the lower limit pressure P _L is the minimum required pressure of the compressor, and the upper limit pressure P _H is a highest pressure that can be acceptable safety. The control time T is set based on the lifetime of the compressor and its peripheral devices. Further, the storage unit 36 has a minimum load pressure P _M set higher than the lower limit pressure P _L and close to the lower limit pressure, and a pressure lower than the upper limit pressure P _H and close to the upper limit pressure. The set unload acceleration pressure _PP is stored.

Unload control unit 38, the discharge pressure P is in the lowest load pressure P _M or more pressure region, after the control time T to the time of loading quantity changes as a starting point t ₀ of the compressor has elapsed, the starting point t ₀ When the pressure change amount ΔP from is equal to or larger than the set increase amount ΔP _S (> 0), the electromagnetic switches 16a to 16d are controlled to reduce the number of compressors loaded by one (hereinafter referred to as “ This is referred to as “first unload switching control”).
Furthermore, the unload controller 38, after the control time T from the start t ₀ has elapsed, when the discharge pressure P is in the unload promote pressure P _P above pressure range, by controlling the electromagnetic switch 16a~d Then, control is performed to reduce the number of compressors loaded by one (hereinafter referred to as “second unload switching control”).

Lower limit pressure control unit 40, the discharge pressure P detected by the pressure sensor 24 is, when lowered to the lower limit pressure P _L, preferentially to switch to load a single compressor from the unload, electromagnetic switch 16a Control ~ d. The upper limit pressure control unit 42, the discharge pressure P is when it reaches the upper limit pressure P _H, preferentially to switch to unload one compressor from the load, it controls the electromagnetic switch 16a-d. As the control time T, for example, a time zone such as 60 to 240 seconds is selected.
The lower limit pressure P _L or the upper limit pressure P _H is set based on the upper limit pressure set in the compressor itself or the consumption rate of the compressed fluid, and the setting method is not particularly limited to these methods.

Next, the operation procedure of the compression apparatus 10 in this embodiment will be described with reference to FIGS. First, in FIG. 7, at the time of starting the operation as well as to load the entire air compressor 12A～d, simultaneously the timer 32 measures the time t as a starting point t ₀ the operation start point (step 11). As a result, compressed air begins to be stored in the air tank 22 and the pressure detected by the pressure sensor 24 increases. Discharge pressure P is below the lower limit pressure P _L, and reaches the low load pressure P _M (step 12), and starts the first unload switching control, to restart the timer measurement at this point (step 13). A control procedure of the first unload switching control will be described with reference to FIG.

In FIG. 8, in the first unload switching control, the time t measured by the timer 32 is compared with the control time stored in the storage unit 36, and when the measured time t passes the control time T (step 31). The calculator 34 calculates the change amount ΔP of the discharge air pressure P from the start point t ₀ (step 32). When the change amount [Delta] P is set increment [Delta] P _S above, after the compressor has confirmed that it is not a whole number unloaded state (step 33), it switched to unloaded from loading a single compressor (step 34). This time of switching is re-started measuring the time t by the timer 32 as a starting point t _0, and ends the first unload switching control here. The setting value [Delta] P _S, in consideration of the compression performance of the compressor 10, is appropriately selected from positive.

  If NO in step 31 or step 32 or YES in step 33, unload switching control is not performed.

Returning to Figure 7, after the first unload switching control is finished, the discharge pressure P reaches the unloading promote pressure P _P (step 14), when I further reached unload promote pressure P _H (step 15), priority One compressor is automatically and automatically switched from loading to unloading, and at the same time, timer measurement is restarted (step 16). In step 15, if not yet reached the unloading promote pressure P _H, performing second unload switching control (step 17).

In step 14, when the discharge pressure P does not reach the unloading promote pressure P _P, compared with the lowest load pressure P _M (step 18), the discharge pressure P is equal to the lowest load pressure P _M or more, the process returns to step 13 Then, the first unload switching control is repeated again. In step 18, when the discharge pressure P is not minimum load pressure _{P M} or more, comparing the discharge pressure P and the lower limit pressure _{P L} (step 19). When the discharge pressure P is lower than the lower limit pressure P _L, the compressor after confirming that it is not a whole number loaded state (step 20), it switched to load the compressor one from the unload (step 21). When not less than the lower limit pressure P _L, the process returns to step 12.

As a starting point when the discharge pressure P of the compressed air reaches the lower limit pressure P _L (corresponding to point t ₁ in FIG. 10) to start the measurement of the time t by the timer 32. Counting time t of the timer 32 is compared with the reloading time limit T ₁ stored in the storage unit 36 (step 22), after said measured time has exceeded the reload time limit T _1, the discharge pressure P is still lower pressure when below the P _L (step 23), further switches to load the compressor one from the unload and re-started at the same time measuring timer 32 time (step 21). When the discharge pressure P is below the lower limit pressure P _L, performs repeat control step 21 → step 24, when the discharge pressure P is returned to the above lower limit pressure P _L, the process returns to step 12.

Next, the control procedure of the second unload switching control will be described with reference to FIG. 9, the time of loading quantity change of the compressor starting point t ₀ and the time t has passed the control stop time T (step 41), and when the elapsed after the discharge pressure P is unloaded promoting pressure P _P or (Step 42), it is confirmed that all the compressors are not unloaded (Step 43). In step 42, when the discharge pressure P is not _{equal to} or higher than the unload acceleration pressure PP, the process returns to step 12. If NO in step 41, or if all the compressors are unloaded in step 43, unload switching control is not performed.

When all the compressors are not in the unloaded state, the electromagnetic switches 16a to 16d are controlled by the unload control unit 38 to switch one compressor from loading to unloading, and at the same time, the timer 32 measures time t ( Step 44). Here, the second unload control is terminated. Then, the process returns to step 14 in FIG. 7, where the discharge pressure P is equal to or unloaded promoting pressure P _P above is repeated a second unload switching control again.

FIG. 10 shows an example of operation control of the compression apparatus 10. In FIG. 10, all the compressors are loaded at the start of operation. This operation start time is regarded as a time when the number of compressors loaded is changed, and is set as a start point t ₀ of the control stop time T. Discharge pressure P begins to rise, exceeding the lower limit pressure P _L, reaches the minimum load pressure P _M, when in the pressure range in between the lowest loading pressure P _M and the unloading promoting pressure P _P is like this First unload switching control is performed.

When the discharge pressure P is in the low pressure area between the lower limit pressure P _L and the lowest load pressure P _M, the first unload switching control is not performed. When the discharge pressure P has decreased to the lower limit pressure P _L is automatically and preferentially perform load switching control to switch the load to the compressor one from the unload.
When the discharge pressure P becomes lower than the lower limit pressure P _L, and the time when the discharge pressure P has decreased to the lower limit pressure P _L with starting point t _1, the lower limit pressure even after the lapse reload time limit T ₁ is from the start point t ₁ when is P _L or less, switch to unload further the compressor one from the load. Until re-load limit time T ₁ has elapsed not perform the switching to the load. Reload time limit T _1, for example, time zone, such as 1 to 5 seconds is selected.

According to the present embodiment, the control time T is set based on the life of the compressor and its peripheral devices, and after changing the number of operating compressors, the number of operating compressors is not changed within the control time T. As a result, the control frequency of the compressor can be reduced to prevent the compressor from being damaged or the motor from being burned out. Further, when the pressure change amount [Delta] P in the discharge compressed gas after the control time is set increment [Delta] P _S above, since the compressor one from the load were to switch to unload, discharge compressed gas of the compressor 10 The overall pressure can be kept low. This makes it possible to reduce power consumption and improve the life of the compressor.

Also, when the discharge pressure P is lowered to the lower limit pressure P _L, automatically and preferentially perform load switching control to switch the load to one compressor from the unload. Thus, the discharge pressure P is prevented from falling from the lower limit pressure P _L, can be operated compressor within the proper pressure range.

Also, when the discharge pressure P is below the lower limit pressure P _L, after the first time the load control, the reload time limit T ₁ is not passed, it is not carried out a second time load control. As a result, frequent switching between unloading and unloading of the compressor can be prevented, and failure of the compressor and burning of the motor can be prevented.

(Embodiment 2)
Next, as a second embodiment, another pressure control example of the operation control of the compression apparatus 10 will be described with reference to FIG. FIG. 11 shows an example of pressure control during operation. In the figure, each time the discharge pressure P in the low pressure area is lowered to the lower limit pressure P _L, is performed to load switching control. When the medium pressure range, after the control time T as a starting point t ₀ the number of operating time of changing of the compressor has elapsed, it is the pressure change amount [Delta] P from the starting point t ₀ is set increment [Delta] P _S or unload Switching control is performed.

In the high pressure region between the unload acceleration pressure P _P and the upper limit pressure P _H , after the control time T with the start point t ₀ as the time when the number of operating compressors is changed, the discharge pressure P becomes the unload acceleration pressure P. _{When P is} greater than or _{equal to P,} unload switching control is performed to switch one compressor from loading to unloading. Also, when the discharge pressure P reaches the upper limit pressure P _H, even before the lapse of control period T, performing automatically and preferentially unloaded switching control to switch to unload one compressor from the load ing.

According to this embodiment, when the discharge pressure P is in the high pressure zone, after the control time T as a starting point t ₀ the number of operating time of changing of the compressor has elapsed, the discharge pressure P is unloaded promoting pressure P _P or If so, since the unload switching control is performed, the descending speed of the discharge air pressure P in the high pressure region is increased. This makes it possible to reduce power consumption and prevent malfunctions of the compressor.

Further, when the discharge pressure P reaches the upper limit pressure P _H is automatically and so is performed preferentially unloaded switching control, and prevent the compressor is overloaded, compressed with appropriate pressure range You can drive the machine.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at the energy-saving operation which suppressed the pressure of the discharge compression gas of a compressor, the control frequency of a compressor can be decreased and the failure of a compressor, the burning of a motor, etc. can be prevented effectively.

DESCRIPTION OF SYMBOLS 10 Compressor 12a-d Air compressor 14a-d Motor 16a-d Electromagnetic switch 18 Power supply 20 Collecting discharge piping 22 Air tank 24 Pressure sensor 26 Compressed air supply piping 30 Controller 32 Timer 34 Calculation part 36 Memory | storage part 38 Unload control part 40 lower limit pressure control unit 42 upper limit pressure controller P discharge pressure P _H upper pressure P _L limit pressure P _M minimum load pressure P _P unloaded promoting pressure T control time T ₁ reload time limit [Delta] P pressure change amount [Delta] P _S set increases Quantity t Measurement time t ₀ , t ₁ start point

Claims (10)

In the operation control method of the compression device that switches between unloading and loading in each compressor according to the flow rate used while detecting the pressure of the compressed gas discharged from a plurality of compressors,
The control time is set based on the life of the compressor and its peripheral devices, and the time when the number of compressors is changed is the starting point of the control time. After the control time has elapsed, the pressure change of the discharged compressed gas from the starting point An operation control method for a compressor, wherein an unload switching control is performed to switch one compressor from loading to unloading when the amount exceeds a set amount.   2. The compressor according to claim 1, wherein when the pressure of the discharged compressed gas drops to a preset lower limit pressure, one compressor is preferentially switched from unloading to loading. 3. Operation control method.   3. The apparatus according to claim 1, wherein when the pressure of the discharge compressed gas rises to a preset upper limit pressure, one compressor is preferentially switched from loading to unloading. 4. The operation control method of the compression apparatus as described.   The minimum load pressure belonging to a pressure range higher than the lower limit pressure and close to the lower limit pressure is set in advance, and the unload switching control is performed in a pressure range equal to or higher than the minimum load pressure. The operation control method of the compression apparatus as described in any one of?   An unload acceleration pressure belonging to a pressure range lower than the upper limit pressure and close to the upper limit pressure is set in advance, and one compressor is loaded when the control time elapses in a pressure region higher than the unload acceleration pressure. The operation control method for the compressor according to any one of claims 1 to 4, wherein the operation is switched from unloading to unloading. Multiple compressors,
A pressure sensor for detecting the pressure of the compressed gas discharged from the compressor;
Unloading means for individually unloading each compressor;
In a compression apparatus comprising a controller that controls the unloading means to switch between loading and unloading of each compressor,
The controller is
A storage unit that stores a preset control time, a timer that measures time starting from when the number of compressors loaded changes, and a time that is measured by the timer exceeds the control time. An unload control unit for controlling the unloading means so as to perform unload switching control for switching one compressor from loading to unloading when the pressure change amount of the discharge compressed gas becomes equal to or greater than the set increase amount; A compression apparatus comprising:   The lower limit pressure of the discharged compressed gas is preset and stored in the storage unit, and the controller preferentially switches one compressor from unloading to loading when the discharged compressed gas drops to the lower limit pressure. The compressor according to claim 6, further comprising a lower limit pressure control unit that controls the unloading means.   The upper limit pressure of the discharged compressed gas is preset and stored in the storage unit, and the controller preferentially switches one compressor from loading to unloading when the discharged compressed gas rises to the upper limit pressure. The compression apparatus according to claim 6, further comprising an upper limit pressure control unit that controls the unloading means.   A minimum load pressure belonging to a pressure range higher than the lower limit pressure and close to the lower limit pressure is set in advance and stored in the storage unit. The compression apparatus according to any one of claims 6 to 8, wherein the unloading unit is controlled so as to perform control.   An unload acceleration pressure belonging to a pressure range lower than the upper limit pressure and close to the upper limit pressure is set in advance and stored in a storage unit, and the unload control unit of the controller performs the control time in a pressure region equal to or higher than the unload acceleration pressure. The compressor according to any one of claims 6 to 9, wherein the unloading unit is controlled so that one compressor is switched from loading to unloading when the time elapses. .

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